It is feared that the emergence of the Omicron strain may reduce the effectiveness of the new coronavirus vaccine.



Among them, the third inoculation that is being promoted.

The vaccine to be inoculated is the same as before, and it is made for the conventional virus.



With the emergence of Omicron strains, we asked experts about the effects and significance of the third vaccination with the vaccine.

There is also a place to hurry with the appearance of Omicron where the third inoculation begins

Nearly 80% of people in Japan have completed the second vaccination, and from December 1st, the third vaccination for medical professionals began.

After the beginning of the year, inoculation will be given to elderly people.



Among them, the infection of the Omicron strain, which has a much larger number of mutations than the conventional virus, is spreading in each country, and some of them, such as the United Kingdom, havetened the third inoculation.

Vaccines that are currently being inoculated around the world are made in response to the conventional new coronavirus.



It is feared that the Omicron strain has many mutations in the spike protein that provides a foothold when infecting cells, making it difficult for neutralizing antibodies that prevent infection to bind and reducing its effectiveness.



(For prevention of aggravation, the CEO of Biontech, a German pharmaceutical company that developed the vaccine with American pharmaceutical giant Pfizer, said in an interview with the American media that it is likely to be effective against Omicron strains as well. is showing)

Third inoculation Some of them bind to Omicron by increasing the number of antibodies.

Kiyoshu Taniguchi, director of the National Mie Hospital, a member of the government's Advisory Committee on the Basic Response Policy, said it makes sense to give a third dose, even if the Omicron strain may reduce the effectiveness of the vaccine. It is said that.

Mr. Taniguchi said, "For example, even if the virus mutates and the effect of the neutralizing antibody is reduced to one-fourth, the booster vaccination enhances the immune function and quadruples the amount of neutralizing antibody. If this happens, the number of neutralizing antibodies that bind to the virus will increase. "



If the amount of neutralizing antibody is increased by boosting the vaccine, some of them will bind to the Omicron strain.

Third inoculation Expected to be effective in preventing aggravation and infection

In addition, Tomoya Saito, director of the National Institute of Infectious Diseases Infectious Diseases Crisis Management Research Center, said in the "Close-up Hyundai +" broadcast on the 7th of this month, if the amount and level of antibodies were increased by additional inoculation, Even if the form of the virus is different, it can be expected to have a certain degree of effect in preventing aggravation and infection.



Saito said, "The vaccine I'm using now has a gradual decline in immunity and defense, so the third vaccination is to raise the level of immunity and maintain it for a long time. Even if the virus does not match, inoculation produces various antibodies to protect it in the body. Not only the antibody that matches exactly, but if there are many that match even a little, the appearance of the virus will change a little. However, by raising the overall defense level, we can expect the effect of suppressing infection and aggravation. "

“Prime and Boost”

It is not just the amount of antibody that is expected for the third vaccination.



A member of the government subcommittee, Director Taniguchi of the National Mie Hospital, National Hospital Organization, said that establishing "immunological memory" with the third vaccination is also an important point.



The vaccine makes the body's immune system recognize that the virus is the "enemy" to be attacked on the first vaccination.



This is called "prime," which means teaching in advance in English.



Then, in the second inoculation, the memory of the "enemy" of what is the target of the attack is fixed in the immunity.



The third inoculation will strengthen the memory and make it last longer.



The third inoculation is called "boost", which means strengthening in English.



It is a strategy called "Prime and Boost" that teaches the enemy something and strengthens its memory.



Mr. Taniguchi said, "Even if a new mutant virus appears due to overlapping mutations, it is possible to avoid aggravation by vaccination and proper immunity, which also applies to Omicron strains. I think it is important to proceed with booster vaccination. "

Should the interval up to the third time be short?

オミクロン株の感染が各国で報告される中、少しでも早く3回目の接種を行うべきでしょうか？



3回目の接種について、厚生労働省は2回目からの接種間隔を原則8か月以上としていて、医療機関や高齢者施設でクラスターが発生した場合などには厚生労働省に事前に相談したうえで施設の利用者や職員に対しては6か月に前倒しできるとしています。



ウイルスやワクチンに詳しい北里大学の中山哲夫特任教授は、オミクロン株に対する効果が低下することを考えても、2回目の接種のあと、6か月から8か月の間に接種するのが妥当ではないかとしています。



一方で、がん治療を受けている人や糖尿病の持病がある人などは、体内に侵入したウイルスなどを攻撃する免疫細胞が働きにくく、免疫力が弱くなっているため、早めの接種も検討すべきだと指摘しています。

Professor Nakayama said, "People who are receiving dialysis, cancer treatment, or treatment with immunosuppressive agents have a level of antibody elevation and immunity induction level even after the second vaccination. Low. Immune cells that are thought to be involved in whether or not the disease becomes severe when infected are also difficult to work. It may be necessary to inoculate early, and it is necessary to discuss whether to inoculate without waiting for 6 months. " I am.



On the other hand, regarding the fact that the interval between vaccinations has been further shortened and that the UK is proceeding with the third vaccination in three months from the second vaccination, Professor Nakayama said that the UK is in a phase of spreading infection and further infection. I point out that it has a strong meaning of not spreading.



Professor Nakayama said, "From the situation in the UK, I think that Japan chose to hit early as breakthrough infections increased from about 3 months and 4 months after the second vaccination. The infection situation is completely different, and so far the infection has been almost suppressed, so it is not possible to vaccinate in 3 or 4 months. In Japan, the infection will spread explosively in the future. If breakthrough infections increase, it may be necessary to determine how long after vaccination and then consider shortening the vaccination interval. "

You should think in "two-stage stance"

On the 8th, American pharmaceutical giant Pfizer and others said that the effect of the neutralizing antibody on the Omicron strain was 25 times higher than that on the second vaccination, which was as high as the effect on the conventional virus. We announced the results of the initial experiments.



Research on the effects of the vaccine on Omicron strains, including the effect of the third inoculation, is currently underway around the world.



You may need a vaccine that is compatible with the Omicron strain, but if that happens, it will still take some time before you can actually get it.



Saito, the director of the National Institute of Infectious Diseases, said that he would consider introducing a vaccine compatible with the Omicron strain if necessary, while confirming the effects of the existing vaccine, including the third inoculation. I'm telling you that you should think about it.